[FFmpeg-devel] [PATCH] Implement guessed_pts in avcodec_decode_video2.

[Michael Niedermayer]

On Tue, Feb 01, 2011 at 05:04:26PM +0000, M?ns Rullg?rd wrote:
> Jean-Daniel Dupas <devlists at shadowlab.org> writes:
> 
> > Le 1 f?vr. 2011 ? 17:44, M?ns Rullg?rd a ?crit :
> >
> >> Michael Niedermayer <michaelni at gmx.at> writes:
> >> 
> >>> On Tue, Feb 01, 2011 at 12:47:17PM +0000, M?ns Rullg?rd wrote:
> >>>> Alexander Strange <astrange at ithinksw.com> writes:
> >>>> 
> >>>>> On Jan 30, 2011, at 2:28 PM, Nicolas George wrote:
> >>>>> 
> >>>>>> 
> >>>>>> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
> >>>>>> ---
> >>>>>> cmdutils.c           |   27 ---------------------------
> >>>>>> cmdutils.h           |   24 ------------------------
> >>>>>> ffmpeg.c             |   14 ++++++--------
> >>>>>> ffplay.c             |   10 +++-------
> >>>>>> libavcodec/avcodec.h |   20 ++++++++++++++++++++
> >>>>>> libavcodec/utils.c   |   43 ++++++++++++++++++++++++++++++++++++++++++-
> >>>>>> 6 files changed, 71 insertions(+), 67 deletions(-)
> >>>>>> 
> >>>>>> This patch moves the guess_correct_pts function from cmdutils to libavcodec.
> >>>>>> The feature is available through a new field in AVFrame, guessed_pts.
> >>>>>> 
> >>>>>> make test and ffplay still work, but I would like to have some more time to
> >>>>>> read it carefully, but I have things to do in the next few days, and this
> >>>>>> feature was discussed in another thread, so here the current version. It
> >>>>>> will conflict with some patches that will certainly soon be applied, so I
> >>>>>> will update and submit it again anyway.
> >>>>>> 
> >>>>>> Regards,
> >>>>>> 
> >>>>>> -- 
> >>>>>> Nicolas George
> >>>>>> 
> >>>>>> [..]
> >>>>>> +\
> >>>>>> +    /**\
> >>>>>> +     * pts estimated using various heuristics, in stream time base\
> >>>>>> +     * - encoding: unused\
> >>>>>> +     * - decoding: set by libavcodec, read by user.\
> >>>>>> +     */\
> >>>>>> +    int64_t guessed_pts;\
> >>>>> 
> >>>>> It's not quite estimated, it's chosen from either pts or dts.  I
> >>>>> think the name should be reassuring - though I can't think of one,
> >>>>> just 'timestamp'?
> >>>>> Also, the comment should say that clients can rely on this as the
> >>>>> time of the frame.
> >>>> 
> >>>> But can they?  The current code certainly doesn't look reliable to me.
> >>> 
> >>> A patch that improves it together with a bugreport that shows an example of
> >>> improvment is welcome.
> >>> 
> >>> besides in how far is this related to this patch?
> >> 
> >> The patch pushes the broken guessing code into lavc, which was up
> >> until now reliable.
> >
> > If it was reliable, why ffplay and ffmpeg had to implement guessing
> > in the first place ?
> 
> Because lavf is unreliable, and because nobody was allowed to touch
> the code.

Patches that fixed bugs where always welcome. Patches that caused bugs where
not, yes thats true

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is dangerous to be right in matters on which the established authorities
are wrong. -- Voltaire
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